This invention relates to a system for providing on-board timing for a vehicle traversing a predetermined course. The invention is applicable for example to sports such as water skiing and allied water sports where an on-board measure of boat speed is required, and also motorcar and motorcycle racing where there is a requirement for lap times and speeds to be conveyed to the drivers.
In water skiing events such as slalom and jumping, the rules require the boat speed to be maintained within certain limits for the run to be valid. For example, in the slalom event the boat traverses a course defined by successive pairs of buoys, the boat being driven between the buoys of each pair whilst the skier executes a prescribed slalom course. To ensure that each competitor receives the same advantage, the boat is driven at a certain prescribed speed, for example 36 m.p.h., and stop watch timing has been used in the past to ensure that the average boat speed over the course does not deviate from the prescribed spped by more than a specified amount, e.g. plus or minus 0.2 m.p.h.
The stop watch-timed period is made by an on-board official using buoys at the beginning and end of the course as reference points. Hitherto this has been considered unsatisfactory as the accuracy of timing is dependent on the official's reflexes and may vary over the course of several runs. Also the average boat speed can only be checked after the boat has completed the course.
Attempts have been made to eliminate the human element in timing but no satisfactory proposal has yet been made. One timing system which has been adopted but which did not progress beyond the experimental stage involves providing inertia-type switches on the entrance and exit buoys of the course which were intended to close in response to rocking of the buoys during passage of the boat, switch closure being effective to trigger a radio transmitter and emit a signal for reception by a receiver on the boat. This system was found to be unsatisfactory for a number of reasons, e.g. the radio transmitter carried by the buoys has to be powered by an on-shore power supply source making it necessary to connect each buoy to the supply source by supply lines of considerable length. Also, the switches were found to be unreliable in that they did not always close in response to passage of the boat.
Another proposal which has been considered is the use of infra-red beams produced between the entrance and exit buoys. However, this has been rejected because of the difficulty of powering the buoy mounted beam transmitters and receivers and associated circuitry, battery power being undesirable because of the considerable increase in the weight of the buoys and hence risk of injury to the skiers in the event of collision at speed with a heavy buoy. Moreover, there is the added complication of achieving beam alignment with the receivers due to vertical and tilting motion of the buoys when disturbed by the approaching boat and choppy water, and of protecting the electrical components from the inevitable environmental hazards.
Thus, whilst the shortcomings of hand timing to check boat speeds have been recognised for many years, no satisfactory alternative has been found.
In the case of motorcar and motor-cycle racing, the usual method of conveying lap times and speeds to drivers is by means of a display board held up at the track side and kept up to date by members of each driver's backup team. Although this is a rather unsatisfactory method bearing in mind the high speeds attained nowadays in for example Formula 1 racing, an acceptable alternative has not hitherto been found.